Talk:Decompression sickness/Archive 1

Archive 1

Headline text

I added the modifier 'pressure' to altitude since that is the correct term when physiological effects are addressed (the term 'altitude' alone is too vague - it may mean the cabin altitude or the actual altitude above sea level) [[User:Crum375|Crum375]] 23:40, 5 May 2006 (UTC)

Altitude-induced decompression sickness

Does anybody know if these are truly identical and need to be merged or should be kept as separate articles? Tidy, tidy, tidy. MeltBanana 13:42, 23 Sep 2004 (UTC)

The conditions themselves (decompresion sickness) are the same. Dissolved gas bubbles out of the blood and/or tissues due to a decrease of pressure. Likewise the treatment is the same, returning to the higher pressure environment (either by landing, or barometic chamber).

The actual causes themselves are very different, one's caused by flying too high, and the other is caused by diving too long. I'm also of two minds about combing the articles — pilots are unlikely to worry much about diving DCS, and vice-versa.

I'll read through both articles careful. If there's significant overlap, then I think we should merge. If there's little overlap, then it would be reasonable for them to remain separate. --PJF ^(talk) 10:29, 28 Nov 2004 (UTC)

While both articles are significantly different in content, I do think they would be better merged, with separate sections on diving DCS and flying DCS. The parts that relate to both (eg, symptoms, causes, etc) can be merged together. The altitude-induced DCS article discusses the symptoms of DCS much better than this one. --PJF ^(talk) 12:27, 28 Nov 2004 (UTC)

DCI = DCS + Air embolism

Some people distinguish between DCI and DCS, see http://www.hyperchamber.com/decompression_illness/

--Mark.murphy 13:27, 04 Dec 2004 (UTC)

Thanks for the edits, there's been a few times where wikipedians have confused DCI and DCS, and there was even an attempt to merge them a little while ago (see Talk:Decompression illness).

I'm currently unsure as the best way to arrange all these articles. Since the treatment for DCS and embolisms are the same, it would seem redundant to have treatment listed three times (once for Decompression sickness, once for Decompression illness, once for air embolism). It may be worth putting all the treatment under Decompression illness to avoid re-work, or to have a separate article that's transcluded into all DCS/DCI/Air embolism.

Comments and ideas would definitely be appreciated here. --PJF ^(talk) 23:41, 4 Dec 2004 (UTC)

Often DCI stands for Decompression Illness. Michagal 16:45, 13 August 2006 (UTC)

Disclaimer

We are dangerously close to giving medical advice in this article. Someone ought to slap one of those "Wikipedia does not give medical advice" disclaimers on the article. Anyone recall the template? --Dante Alighieri | Talk 23:08, Jun 6, 2005 (UTC)

Suggest adding additional info on relationship of O2 to DCS

Since all US manned space missions before the shuttle used pure O2 at about 5 psi (still used in space suits), an obvious question is how this affects DCS and why. Also divers through equipment failure or error can breath pure O2, and if not killed by oxygen toxicity, if they make a sudden emergency ascent, does O2 gas evolution cause DCS. If not, why not. Joema 00:03, 24 December 2005 (UTC)

Here are some reasons why equilibrating nitrogen might be more of a problem than equilibrating oxygen.

• Nitrogen diffuses in water at half the rate of oxygen.
• Nitrogen does not have proteins that bind and transport it like hemoglobin and myoglobin do for oxygen.
• Nitrogen is not metabolized, unlike oxygen.

These suggest that blood oxygen will come to equilibrium faster with air than nitrogen when the pressure changes, perhaps so rapidly that it is unlikely to produce bubbles.

--AJim 18:08, 29 March 2007 (UTC)

Having just become NITROX certified (because I was on a week-long dive trip and most divers were using NITROX, which didn't exist when I learned diving) and finding the theory given to me wholly unconvincing to someone with a Physics degree, I had a similar question as Joema. I checked the wikipedia NITROX page and found the same theory regurgitated without any reflection. I think it would be worthwhile for someone to research this and add it to this page (with a reference from the NITROX page).

Of AJim's three reasons I find the first one credible, but not the other two. The chemical binding of oxygen to hemoglobin should be a process independent of the physical solution of oxygen gas in the water component of blood, unless the bound oxygen is in an equilibrium with the dissolved oxygen, and the rate of transfer is small compared to the exchange of bound oxygen in lungs and muscles. Without further information I consider this unlikely. For the same reason, the fact that oxygen is metabolized seems irrelevant.

Some definite info from an expert would be appreciated.

Heiser (talk) 01:39, 12 January 2008 (UTC)

Oxygen can supersaturate tissue and "contribute" to decompression sickness (DCS). Dr. K. W. Donald made observations at the Royal Navy Physiology Lab where they exposed goats to 64% Oxygen and 36% Nitrogen at 5.54 ATA and rapidly decompressed them. The animals suffered "grave" DCS that resolved "rapidly without recompression". They were unable to show symptoms of DCS with 100% Oxygen. They concluded that "providing a certain degree of supersaturation (oxygen) when nitrogen is present, the initial risk of dangerous bubble formation can be greatly influenced by increased tensions of oxygen in the body". from: Donald KW. "Oxygen Bends" J Appl Physiol. 1955 May;7(6):639-44. PMID 14381341. -Gene Hobbs (talk) 19:35, 18 March 2008 (UTC)

Kenneth Donald's work often involved exposures to oxygen levels far beyond what is now likely to be a realistic scenario when diving ("Oxygen and the Diver" is well worth a read). It is difficult to envisage a diver being exposed to the nitrox he used in the goat experiments quoted above. Even so, it is notable that Donald was unable to induce DCS using 100% oxygen. I might conclude that the goats exposed to a partial pressure of 2 bar of nitrogen (equivalent to 15 metres on air), when rapidly decompressed, experienced DCS due to nitrogen bubbles forming.

With regards to AJim's assertion that oxygen in solution will either be taken up by haemoglobin or metabolised, it is necessary to remember that the pressure in the arterial system is considerably higher than in the venous. This leads to the observed result that on decompression, bubbles form first within the venous system. Unless the partial pressure of oxygen is extremely high, the haemoglobin in venous blood is not fully bound. Both nitrogen and oxygen are pretty insoluble in water - a tiny amount volume/volume is in solution in equilibrium. Thus any dissolved oxygen which might form bubbles (as the pressure drops) can reasonably be expected to be picked up by the unbound haemoglobin within the venous system - haemoglobin has a huge affinity for oxygen. Similarly, tissues surrounding veins are likely to be able to metabolise excess oxygen - from what I understand, that is a very fast process.

Taken together, I have little reason to doubt "that blood oxygen will come to equilibrium faster with air than nitrogen when the pressure changes, perhaps so rapidly that it is unlikely to produce bubbles". I suppose a scenario could be constructed where the oxygen partial pressure is so high and the decompression so rapid that oxygen bubbles could form within the arterial system and then be able to exist for a prolonged period. But I doubt whether that could translate into a possible scenario within the current bounds of diving - a very deep dive using a rebreather which malfunctions and somehow puts 100% oxygen into the loop long enough to come into equilibrium in the body, followed by rocket ascent to the surface? I still think you would succumb to oxtox or have sufficient nitrogen or helium in your system to cause DCS without worrying about the possibility of oxygen bubbles :) All this is just my very humble opinion, of course - is it enough to answer Joema's original question? --RexxS (talk) 00:52, 22 March 2008 (UTC)

"Bends" refering only to non-neurological symptoms?

Since when does the term "the bends" refer only to type I DCS? I think this article should be changed to classify DCS/DCI into type I and II instead, and "the bends" should be described as a colloquial term for all DCI. -- David Scarlett^(Talk) 01:36, 20 July 2006 (UTC)

There are 2 separate points:

1. The "bends" was originally DCS in joints but is now slang for DCS generally. DCS in joints is only Type I DCS. The "bends" should only be mentioned in connection with slang and DCS in joints.
2. Types I and II DCS should be explained. They may be a good abbreviations for professionals who use them often but the abscence of meaning in those terms make them difficult to remember and a barrier to communication for infrequent users, so I don't think it would be useful to structure the symptoms around Type I and Type II.

Mark.murphy 19:01, 20 July 2006 (UTC)

US specific remarks

• Upon landing seek medical assistance from an FAA medical officer. And if you're not in the US should you travel there to find an FAA medical officer or should you consult a medical officer of your own aviation authority? I'll change "FAA" to "aviation authority".
• These sections look to me like they came from an official publication. If that's a US government one which is not copyright then I imagine that's OK but perhaps it would be useful to cite the source. EdDavies 21:54, 16 September 2006 (UTC)
• Much of this article appears to have been plagiarized from FAA publication AM-400-95/2 JSB73 10:03, 28 January 2007 (UTC)
• When was it allegedly plagiarized? It has been edited more than 50 times. Is "FAA publication AM-400-95/2" on the internet, and if so where, or where to get a copy to check? Anthony Appleyard 14:12, 28 January 2007 (UTC)
  • It appears to have happened in the edit of 11:38, 29 November 2004 as a result of the merge with altitude induced decompression sickness. The publication does not appear to be online from an official government source, however a google search turns up a document purporting to be the same publication (http://www.2pi.com/les/flying/faa_400altitude.html) while a more general search turns up a current FAA document that looks like a recent revision of the earlier pamphlet (http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/DCS.pdf) I don't believe this is copyright infringement, simply copying without correctly crediting the source. JSB73 05:09, 29 January 2007 (UTC)

Wikipedia:Avoid trivia sections in articles

Thanks in advance. El_C 17:31, 14 April 2007 (UTC)

I support the removal of the trivia section. Non-encyclopedic and half of it was POV anyways. Leuko 17:34, 14 April 2007 (UTC)

You: agree with everything I say [O...kay]; you: disagree with everything I say ["Sorry, English not so nice"]; and you: get morally outraged at everything I say ["That's permanent marker, you know!"]. Wow, you guys are good! El_C 17:54, 14 April 2007 (UTC)

Time?

• How long after the activity does it take for dcs to prove fatal?

Decompression tables external link

• I added a link to [1] http://www.divetables.org (a site that lists all the various deco tables) I was given a spam warning! - this was certainly not my intent - do you think that this is reasonable or was I out of line in listing this page? 01:52, 6 September 2007 User:24.36.27.164
• I have restored this link. It has useful pointers to several decompression tables (as well as matter that could be treated as advertisement). Anthony Appleyard 05:26, 6 September 2007 (UTC)
• Thanks Anthony - I also added the link in the Dive tables category - probably the best place for it - I think it is still relevant here too tho' —Preceding unsigned comment added by 24.36.27.164 (talk) 05:43, 6 September 2007 (UTC) I was going to put it on the main Scuba section too - as a diver myself I found the central repository for tables useful but I will wait for your input on that - cheers
• I have removed this link because

1. It was spammed into a number (11+) WP articles all from the same anon IP.
2. It contains an objectionable amount of advertising per WP:EL - more than 75% of the page are ads, referral links, etc. Obviously, the link was added to drive traffic to the site.
3. A free non-commercial government source exists, which is what I've replaced this link with.

I really don't feel that the commercial site offers any advantages over the non-commercial site to outweigh the WP:SPAM concerns. Anyone disagree? Leuko 06:27, 6 September 2007 (UTC)

Not me. Deleting content is almost always not good, if the content adds at all to the encyclopedia. SPAM is not good (and this certainly WAS spam from the way it was added), but it's very hard to say this definitively for single additions, as some spamoid stuff comes with extras that we need. With net-sites you tend to do what you do with all media-- you try to find the link to the site which minimizes advertising to information ratio. If it can't be zero'd, you pick next-best, for the time being. If you've found a non-comercial site which is as good, then use that, as you've done, and then that's an improvement. I'm only for deleting a commercial link if no link can be found to replace its info. In some cases, I think a link with ads is an improvement even over a (bare) cite to a library work, but of course you should include both.

And after a bit of thought, I will add something else that not every editor will agree with, but which I think conforms with overall policy: you should in some cases try to forget the source of material and ask only whether or not it improves the encyclopedia. In some cases the motives of the content-adder may be less than pure. But people with bad motives can still add useful content. If they do, keep it. Try to separate the intent of spam from its effect. It might be entirely appropriate to warn a spammer, but keep what they've put up! Fortunately, in this case we don't have to choose betwee content and advertisement, because an alternative was found. But that doesn't always happen. SBHarris 02:35, 22 March 2008 (UTC)

Meaning of [Grecian] Bends

The construction: '... known as "The [Grecian] Bends" ...' implies that it was derived from "The Grecian Bends" and became "The Bends" in common usage. I'd rather not lose that implication for the sake of an internal wiki-link: Grecian which leads to an article with no relevance to this article. I'm not sure if there's a way to have both. --RexxS (talk) 02:06, 3 October 2008 (UTC)

Raptures of the deep

"Raptures of the deep" refers to narcosis, not DCS. For Cousteau, see e.g. Silent World here - found quickly on google. What is described occurs at depth, not post-ascent and is clearly narcosis. I'd be happy to see "Raptures of the deep" put back into this article if anyone can find a WP:RS that links the term with DCS. --RexxS (talk) 05:18, 11 October 2008 (UTC)

Scuba diving before flying

I reluctantly reverted a re-wording in the section "Scuba diving before flying" because it removed some well-sourced content. However it added some extra information about PDCs calculating time-to-fly. Perhaps either the extra information can be incorporated without losing the present content (preferably with some further cites to support the additions) or a third opinion will agree with User:72.199.248.230 that the edit is better than the original. --RexxS (talk) 20:38, 1 March 2009 (UTC)

MOSMED and request for collaboration

Following the extensive, excellent, efforts by Ex nihil to improve both DCS and DCI - not forgetting Gene's invaluable referencing - I've tried to give the same structure to this article as WP:MOSMED dictates. Not only does it give medical-related articles a consistent "shape", but more importantly, it helps editors to organise the article by grouping together content in a way that reveals any shortcomings and duplication. At present, there are two whole sections missing on "Diagnosis" and "Prognosis" and room for expansion on several of the existing sections. I'd encourage anyone with an interest in the subject to help improve this article by filling in the gaps and trimming the redundancies. I'm happy to do what I can, but collaboration is much more fun and produces a better article in the end. Help us out! --RexxS (talk) 00:32, 18 April 2009 (UTC)

• Well, I think it's starting to improve. Feel very free to undo any of my efforts, I've swapped stuff around fairly radically, not there yet. I'll be back in Timor Leste on 56kbps soon so I won't have any badwidth to do this. Ex nihil (talk) 09:42, 19 April 2009 (UTC)

Yes, it's looking much better. I think that when the article gets reviewed for conformity with MOSMED, the section on "Predisposition" will have to be a subsection of "Causes", but we can worry about that later. I also feel uncomfortable with having too many sub-levels in an article, but think that we will eventually have to accept one more level than we have at present for "Individual" and "Environmental". "Helium" is a problem. It isn't really part of "Mechanism (Pathophysiology)", as there's no evidence that helium has a different mechanism. I suspect that it should be a subsection of "Causes", standing alone as a sort of by-the way note. The "Mechanism" section needs expanding anyway to discuss the hypotheses of possible mechanisms. I'll re-read the chapter in Bennett & Elliott that I quoted in the bibliography and see what I can add. The whole article needs more referencing and needs {{fact}} tags adding where we think a cite is needed (Gene is great at spotting those and finding the best ref!). --RexxS (talk) 12:54, 19 April 2009 (UTC)

The timing of this is GREAT! Two weeks ago, the Undersea and Hyperbaric Medical Society released their scientific workshops that we scanned for them in 2005. I have been spending most of my free time getting these online. The one I am working on now is the 1991 "What is Bends?" workshop that will be some help for this article. By Tuesday or Wednesday I should be able to get "Treatment of Decompression Illness." in your hands. All of the workshops listed here, see the FAQ page if you have a hard time with these LARGE pdf's (some are 300+ MB). As for Helium, should the section be other breathing gasses so we are not excluding neon, hydrogen, etc.? I'll get the refs above added and note if they can be used to expand sections. --Gene Hobbs (talk) 15:57, 19 April 2009 (UTC)

Hehe, I had already had the thought about inert gases - and that prompted me to add something about ICD. I'll put aside some time later in the week to get all your latest additions, my bandwidth to the house can handle those pdf's :) --RexxS (talk) 16:45, 19 April 2009 (UTC)

• I have cleaned up Causes because I belive they were confused, see section below. In the process I relocated Inert gasses - again. I know Inert gasses has been wondering around for a while and I don't know it is in the right place now. I took it out of Causes because in themselves they aren't one, they are just implicated along with a lot of things like the blood they are dissolved in. Inside Mechanism there is already a discussion on inert gasses, that is where it belongs and that is where I have parked it for now. If it stays it needs to be knitted into the text a lot better. Mechanisms is messy and repeats material elsewhwere, needssome help. Ex nihil (talk) 00:47, 23 April 2009 (UTC)

Confused causes

• Diving at altitude is not a cause of DCS it just exacerbates a cause; the causal mechanism remains identical to diving at sea level. The only issue here is that sea level dive tables are incorrectly calibrated for altitude. I have parked the text here rather than delete it in case it has an application but my feeling is that it has none in this article. Maybe it belongs in Predisposing factors. Whatever happens, the last sentence in parentheses should not go back into the article in any form as it is a red herring. It concerns itself with AMS, HACE and HAPE, which have no connection whatesover with DCS other than they are problems arising from low pressure and also because it isn't correct anyway - altitude sickness symptoms such as oedema have much more to do with the alkalinisation of the blood arising from low pp of carbon dioxide at altitude than they do with hypoxia. The reference given at the end of the parenthetical sentence is not relevant to DCS in particular or to diving in general. I have moved this to Predisposing factors for the time being. Ex nihil (talk) 00:29, 23 April 2009 (UTC)
• Diving before flying is also not a cause it just exacerbates a cause; the causal mechanism remains identical to diving at sea level. The only issue here is that sea level dive tables are calibrated on the assumption the diver will remain at sea level through the outgassing period. I have moved this to Predisposing factors for the time being. Ex nihil (talk) 00:29, 23 April 2009 (UTC)

I have to disagree. According to WP:MOSMED, "Mechanism" (or Pathophysiology) is the means by which the condition affects the body. In this case, it is the way in which bubbles of gas, forming in the joints, skin, venous system or spinal chord, affect those parts. It is indeed the same no matter what the altitude, so the mechanism section should not discuss those different causal factors. "Causes", on the other hand, is the section describing all of the factors which can lead to the condition. This must include discussion of the effects of altitude as that is a factor in causing DCS. I really think the article had the correct structure before the last changes. If you're not convinced, shall I ask for a third opinion at the Doctor's Mess? Cheers --RexxS (talk) 22:24, 23 April 2009 (UTC)

I re-read the pathophysiology and mechanisms in MOSMED and I still consider neither are causes both are a misunderstandings of the assumptions built into the dive tables. However, I don't mind if you revert it but I would be interested in the Doctor's Mess having a look first and will bow to their collective wisdom. Technically not even ascent from depth is a cause, we all do that when we dive, but ascending too fast is and we should reword that cause. Diving at altitude is not a cause, it's quite safe, I've done it but using the wrong tables for your altitude makes you vulnerable to the cause as does: misreading the tables, ignoring or misunderstanding the tables, using out of date tables. The cause remains the same - improperly managed decompression. If we accept these as causes then we open ourselves to a hundred bizarre scenarios also competing as causes; spending your day at the bottom of a South African gold mine and then going diving on sea level tables; a nurse does her spell in a hyperbaric chamber and decides to spend the evening diving; the caison worker manages his caison exit perfectly and assumes a zero surface interval for diving; the plane decompresses violently at altitude and gives the pilot DCS but an unpressurised plane on the same flight profile gives the pilot enough time during the climb to allow proper outgassing and he doesn't get DCS. I do not propose we add these, just pointing out that the cause is mismanaged decompression, or maybe diving outside of the correct tables. On reflection I think we need to reword the causes from Ascent from depth, because of course we do that all the time quite safely it should maybe read, Mismanged ascent from depth or ascent from depth outside the div tables, or Ascent from depth too fast. Consider driving a car, driving per se is not a cause of accidents, driving too fast might be. Ex nihil (talk) 03:03, 25 April 2009 (UTC)

I'll get a WP:3O from the Doctor's Mess, I'm sure they will know best. But I should point out that deco tables do not guarantee that you won't get bent. In my 30 years of diving, I've come across dozens of cases of bends within the tables and with all the "correct" protocols taken. I assure you there was nothing mismanaged about a dive one of my buddies did while engaged in a nautical archaeology course, but she got a bend. What was the cause? - ascending from depth, honest. That's how the bubbles formed. Anyway, I'd be happy to see included any causes we can get a source for, so don't rule out the oddball ones just yet! Cheers --RexxS (talk) 03:15, 25 April 2009 (UTC)

It's funny but we really don't know the cause. We do know that supersaturation and bubbles are involved but that's really all we're sure of. But don't take my word for it:

• GUE (2006). The Mysterious Malady: Toward an understanding of decompression injuries (DVD). Global Underwater Explorers. Retrieved 2009-04-25. - From the mouths of the researchers.
• Nashimoto I, Lanphier EH (eds). (1991). ""What is Bends?". 43rd Undersea and Hyperbaric Medical Society Workshop". UHMS Publication Number 80(BENDS)6-1-91. Undersea and Hyperbaric Medical Society. Retrieved 2009-04-25. {{cite journal}}: Cite journal requires |journal= (help) - from a workshop on the topic.

A discussion of exact mechanisms is just as difficult... Good luck with the WP:3O. --Gene Hobbs (talk) 15:48, 25 April 2009 (UTC)

IMO it you need to add these to a section on predisposing conditions. This has been done and I think it is good they way it is now.--Doc James (talk · contribs · email) 19:52, 25 April 2009 (UTC)

Thanks to all for your help! Cheers --RexxS (talk) 20:25, 25 April 2009 (UTC)

Images

I've added a few obvious images already in use in related articles. If anyone has any better images (e.g. a showing right-to-left shunt, maybe with bubbles; or treatment in a multiplace chamber), please add them or replace the ones there now. --RexxS (talk) 22:53, 25 April 2009 (UTC)

Remaining sections

I've now added the missing sections for "Diagnosis" and "Prognosis" and put those nasty {{expand}} templates on, that Gene hates <grin> - and I've also requested expansion for the history section: a few things must have happened since 1908. I'll remove the templates next week if we haven't attracted any more contributions in the meantime. --RexxS (talk) 23:22, 25 April 2009 (UTC)

You got me... <g> What would be considered notable since 1908? Hill in 1912; Workman's M-values in 1957; Weathersby, Homer and Flynn in 1982, Bühlmann in 1984? All of these are notable as major advances in decompression modeling but not DCS itself. For treatment, I guess it might be worth mention of the first standardized recompression procedure in 1924, Al Behnke's seperation of AGE from DCS (30's) with the first use of oxygen on recompression in 1935, and Golding et al. naming DCS as Type 1 and 2 in 1960.

...or should we expand to the greater detail from Chris Acott? (ref name=five at the moment)

• Acott, Chistopher (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society journal. 29 (2). ISSN 0813-1988. OCLC 16986801. Retrieved 2008-04-25.

So, how much history is appropriate? (you are doing an amazing job here BTW) --Gene Hobbs (talk) 01:52, 26 April 2009 (UTC)

Tough question. But you answered it - the stuff that's notable. The encyclopedia should have content that appeals to the reader - I think that's the key. What are going to be the most interesting milestones for the likely audience? I suppose we can only guess at that - I'd like to know about the first recompression procedures; the first uses of oxygen; Haldane's experiments on goats and the first empirical tables; the first models - obviously Workman & Buhlmann; the timeline for pre-breathing protocols; maybe even the first dive computers (do you remember the Edge?). I know it's not all perfectly on topic, but if we go wrong, somebody will tell us. Put in whatever interests you, Gene; I'll catch up tomorrow with whatever I can add, then see if if we can find a good pic to go with it. Where's Legis when you need him? --RexxS (talk) 03:29, 26 April 2009 (UTC)

Hi, I'm travelling on business at the moment, although I don't think even I could rustle up a picture of an Edge! --Legis (talk - contribs) 16:46, 27 April 2009 (UTC)

There's one here, but it's small and copyright. I knew a diver who had one, but I've not seen him for years. I'll keep searching, but we might have to add a picture of a later pdc and caption it appropriately. I've got an Aladin Pro that's almost 20 years old, which might classify as "classic"! --RexxS (talk) 17:37, 27 April 2009 (UTC)

Carl Spencer's death

Sadly, reknown British diver Carl Spencer died in a decompression-sickness-related deep-diving accident [[2]], reported just today, 2009-05-25. He was diving in 300-feet (120 m) in the Mediterranean at the wreck of Titanic's sister ship Britannic, a bit "larger than the Titanic and deemed equally “unsinkable”, [which] sank in 57 minutes after hitting a mine in 1916 while serving as a First World War hospital ship. The wreck was discovered by Jacques Cousteau, the French underwater explorer, in 1975 but, at a depth of about 304ft (120 metres)." More info on Carl here -- apparently, there is a book out about a number of deep/extreme divers. N2e (talk) 15:26, 25 May 2009 (UTC)

Why reverted?

Please explain where this is covered? The page states:

Decompression time can be significantly shortened by breathing rich nitrox (or pure oxygen in very shallow water) during the decompression phase of the dive.

What I want to state is that decompression can also be reduced or totally not needed if less nitrogen is used DURING the dive. --Stefan ^talk 03:07, 9 July 2009 (UTC)

• To be frank I reverted: Breating nitrox during a dive will also reduce or remove the nessesarcy decompression since less nitrogen will be absorbed.(sic) a bit hastily largely because it comes across as being writtten in a bit of a hurry and things like spelling and English needs a look at. In fact on rereading the previous para you are right and the use of nitrox during the dive is not covered even though using it during the dive is the principal way it is used. It would work better if your use during was integrated properly into the existing use on decompression. Why don't you rewrite the existing paragraph to cover during AND decompression and make the DURING clear as you have done above. My apologies, I should have fixed it rather than just deleted it. Ex nihil (talk) 05:01, 9 July 2009 (UTC)

OK, my english sucks I know :-) I tried integrating it first, but the grammar got very messy, so I decided to do it in a separate section instead. Will try again when I have more time. --Stefan ^talk 05:24, 9 July 2009 (UTC)

I've taken a shot at adding the gist of what Stefan was saying by adding to the end of that paragraph. Please feel free to edit it mercilessly until you get it right. Cheers --RexxS (talk) 19:13, 9 July 2009 (UTC)

Following the last edit, doesn't it leave the reader wondering why 100% oxygen isn't used for all dives, since there would be no DCS? --RexxS (talk) 00:43, 10 July 2009 (UTC)

Gasses are tricky. Oxygen, (including enriched gasses such as nitrox) are potentially dangerous because of Oxygen toxicity. Pure oxygen can kill at quite modest depths, but you wouldn't get DCS. Ex nihil (talk) 03:28, 10 July 2009 (UTC)

Not sure what is best. I agree that Oxygen toxicity should be mentioned here, but the way it was written, nitrox only had effect at or above MOD, which is wrong. Feel free to edit it mercilessly until we get it right. I also would like to change the "(or pure oxygen in very shallow water)" just before, what is very shallow and why do we state that? Not very clear now. --Stefan ^talk 07:20, 10 July 2009 (UTC)

Actually, Donald proved you can have "oxygen bends"... ;) --Gene Hobbs (talk) 10:51, 10 July 2009 (UTC)

Pfft - "these paralyses were presumed to be due to oxygen bubbles". Hehehe - those goats again. Donald had the goats breathing 30%N2/70%O2 at 135 feet (41 m) for 20 mins, followed by 200 feet (61 m) for 5 mins, then decompressed them at a rate equivalent to 120 ft/min (36 m/min). The nitrogen loading would be light, although not negligible, but the rocket ascent would be bound to put N2 bubbles into the blood. I'd be tempted to point to the occasional initial increase in DCS symptoms, when a bent diver is put on 100% O2, as better evidence of O2 bubbles.

@Stefan, 100% O2 is commonly used at 20 feet (6 m) as the deco gas of choice for extended decompression. --RexxS (talk) 17:16, 10 July 2009 (UTC)

I know, what I mean is that very shallow is very unspecific word unless you already know this. --Stefan ^talk 02:22, 11 July 2009 (UTC)

Comments

OK, looks like we have some very competent writers keeping serious track of this page and this is tricky subject, so I will ask before I become BOLD and STUPID :-).

I see several issues with the Predisposing factors section:

• It is VERY specific, talks about 5500 m, 2400 m and 300 m, but this is a gradual process, I do not think we should state limits in meters.
• It is very altitude centric
  • Repetitive ascent: talks about getting altitude DCS, not DCS and only about repetitive ascents above 5500m, same applies to repetitive dives.
  • It talks about time at altitude, but not time at depth. Which is really the same, or totally the opposite or ... you get my meaning? Either have 2 statements, one stating that it takes time to get bent, so when flying, if you decend fast you will be ok and one that it takes time to absorb enough gas to get bent when you get up, or try to do one statement that covers both.
• Diving before moving to altitude and Diving at altitude is really same as Magnitude of the pressure reduction ratio and should really be described under that section.
• I also fitness level is a individual factor or is that OR? Not sure if there is any RS for that?? I'm sure GUE have written something, not sure if they are good enough as reference?

Comments?? --Stefan ^talk 08:05, 10 July 2009 (UTC)

• The specific heights mentioned are sourced and are used in different contexts: 18,000 ft (5,500m) is the height of an aircraft at which the risk of DCS following depressurisation become significant; 8.000 ft (2,400 m) is the equivalent height that the pressure inside aircraft is often set; Although the effect is continuous, dive tables are necessarily discreet. Tables usually have different versions suitable for use over a range of altitudes. Several of these have a "Sea-level" version for use when diving in the 0-1,000 ft (300 m ) range. Diving at higher altitudes on those tables requires moving to a different, more conservative, version.
• I share your concerns about the mixing of DCS from flying (altitude DCS) and diving DCS. However, they are the same condition (AFAIK), and bot should be covered in this article. The challenge is to separate those parts where they differ and bring together the parts where they overlap.
• Diving at altitude requires high-altitude tables or a computer that adapts to altitude. Diving before moving to altitude requires eliminating sufficient excess N2 from the system before decreasing the ambient pressure (often called 'no-fly' time). Not really the same thing, so they need separate descriptions.
• George Irvine at one time certainly believed that fitness was a prophylactic against DCS, but he had a sample size of one. GUE certainly emphasise fitness for diving (and they meet WP:RS for most purposes), but for a specific source that links fitness with DCS, you'd have to ask Gene. --RexxS (talk) 18:02, 10 July 2009 (UTC)

• I struggled while adding references to this article the first time and refrained from making many changes to the text. I am very happy to see this revisited.
• The article is specific in most areas because any research quoted can only predict for the exact conditions tested. But I really doubt making some of this more ambiguous would make much difference.
• Altitude DCS vs Diving DCS. They are very much the same in some respects but other things, like response to treatment, are a whole other ball game. What one really has to understand is the history though. MANY of the things we as divers are told and just assume, like dehydration will increase our chances of DCS, have only really been tested at altitude. Dehydration has never really been shown with a recreational diving study and until 2006, it had not been well described in animal DCS studies (Andreas and Dave's drop out). There is enough dehydration and altitude DCS research to have review articles on the topic. Andreas and Dave describe the problem very well:

"Diving textbooks are filled with potential factors that may alter DCS risk, but many of these have not been tested under controlled conditions. Consequently, the challenge is to identify those that significantly alter DCS risk under a controlled experimental setting."

• Diving research is in trouble. Funding is harder and harder to find, senior researchers are all retiring (2002 study showed 52% retiring in less than 10 years and 96% retiring in less than twenty years), new folks don't stay in the field because the funding is so poor (60% spend less that 10 years). Many of the questions and holes in this article will continue for quite some time given our current progress. Aviation researchers will continue to lead the way on much of this because of the available funding and experienced personnel.
• As for the fitness level question, this is another area that is weak in the data available. We have known for years that "fatness" is a factor (currently ref 23). Albert R. Behnke made an amazing impact on our field but he is still more famous today in the exercise physiology field for his hydrostatic weighing method that is considered the "gold standard" for body fat measurement. This technique started from his interest in how fat stores inert gas and trying to quantify inert gas in the body. True fitness as measured by VO2 max has little real data. The altitude work is again, present and accounted for while the diving data is not really. I can't find my copy of Fitness for Divers but that might be a good reference for what you seem to want.
• I say be BOLD, we will do what we can to help from there. There is just not much to support a significant portion of what divers consider fact. Thanks! --Gene Hobbs (talk) 03:36, 11 July 2009 (UTC)

Well if we will require a reference to every statement and edits like this is revereted then I do not think I will bother. Are we saying that we can not state that repetitive dives increases the risk of DCS, since we do nto have a ref? and we can only state that the risk increases if we are above 5500m and not make a generic statement backed up by a specific reference?? Then I think we are taking the task of having sources way to hard. (maybe I should have removed the reference sure, but still) --Stefan ^talk 09:41, 11 July 2009 (UTC)

I made two edits, if they are reverted I will most likely go away. If they are ok in principle, please feel free to edit them and make them better, referenced and accepted by consensus. I just think that basic stuff is left out now since it is not referenced, and replaced with so specific cases that the page is even worse. --Stefan ^talk 09:57, 11 July 2009 (UTC)

The last two edits you made add useful information and clarify the text. Don't worry too much about cites - we'll find some somewhere. I do believe that almost every sentence ought to be citable: although I don't think that's the same as requiring every sentence to actually be cited - if you see what I mean? I know you intended well, but your previous edit (which I reverted) removed the text that was cited and left the text which was not. Surely taking out sourced material rarely improves an article? Anyway, your last edit removed the ambiguity and improved the article: sometimes we have to go through edit/revert/re-edit until we find better formulations. --RexxS (talk) 12:08, 11 July 2009 (UTC)

I do not worry to much about citing, just thinking it was not realistic as it was. Now I think it is very strange the way the text reads though, with two very simmilar but slightly different sentenses ..... just edit my edits :-) --Stefan ^talk 12:21, 11 July 2009 (UTC)

Some refs can be found in other places as well. There was a workshop on Repetitive diving and it is referenced here (#6). Bet it covers what you are looking for. As RexxS said, just write... I'll do what I can when I have time. Thanks! --Gene Hobbs (talk) 14:11, 11 July 2009 (UTC)

Units

I'm doing some general tidying now, but I can see that we have a mixture of feet (metres) and metres (feet). The Manual of Style allows either, but does require us to be consistent. We need to pick which goes first (feet or metres) and then standardise on that. In the absence of reasons contrary, MOS suggests SI units are preferred, so unless anyone thinks otherwise, I'll regularise the article to metres (feet), etc. later. --RexxS (talk) 13:31, 11 July 2009 (UTC)

Suggested edits

Hi again :-)

I made a few edits, I'm sure you will help me make them better and I hope you will not just revert them, anyway a more controversial edit I will not do, just suggest here, please discuss, all comments elcome, again my issue is that the texts seams to be copied from the sources and not rewritten to fit the article, i.e. DCS in one sentence and decompression related bubbles can we not safely say it is the same??? Also again we only say altitute DCS, when the sources should be enough to cover both.

• Age: There are some reports indicating a higher risk of altitude DCS with increasing age.
• Previous injury: There is some indication that recent joint or limb injuries may predispose individuals to developing decompression related bubblesDCS.
• Ambient temperature: There is some evidence suggesting that individual exposure to very cold ambient temperatures may increase the risk of altitude DCS. Decompression sickness risk can be reduced by increased ambient temperature during decompression following dives in cold water.

--Stefan ^talk 13:54, 27 July 2009 (UTC)

Please consider WP:SYNTH. We have sources stating "xyz about altitude DCS"; we believe altitude DCS is the same as all DCS. Putting the two together to make "xyz about all DCS" is probably beyond what we are permitted to do. If we can find a source that says "xyz about diving DCS", then we can drop the qualifier of "altitude" and cite both sources. But as Gene has pointed out, good research on many aspects of diving DCS is rather thin.

I'll modify your edit here, since South Pacific island natives who for centuries have dived for food and pearls really leaves an ambiguity about whether or not they were scuba diving.

In this edit, your edit summary indicates you think tables are for non-deco dives. Nothing could be further from the truth. Please have another look at the change there: a dive profile includes both depth and time; how can you then choose "maximum time at depth"? Also, the overwhelming opinion in the sources is that alcohol is a risk factor, please reinstate it. The only study that seems to indicate otherwise (Leigh & Dunford) is easy to criticise on two grounds: the presence of a PFO can produce AGE from the mechanism of DCS, thus relating the two and invalidating the statistical method used; and it is very common for the two conditions to be misdiagnosed between each other, thus making the collected reports very unreliable. --RexxS (talk) 15:25, 27 July 2009 (UTC)

I Agree about the edit, your edit makes it better! As for SYNTH you have a point, but I would be surprised if there is no source that states that age is a factor for normal DCS also?? I will not change the text for now

First I did reinstate the alcohol bit just a few minutes after I changed it, sorry, think that the part we have in a earlier part is confusing though, if overwhelming opinion is that it is bad then just state so, now we talk more about the study stating that it does not matter, making it sound like it have no effect.

Secondly my edit summary states tables is for non deco dives also, ALSO beeing the key word, as the text where it was written that tables and computers are used to help calculate deco stops only, I tried to change the text so that it shows that tabels are for showing the maximum time a divier can stay on a deapth withouth having to do deco stops also. Not sure what part of that, is further from the truth, please clarify what you mean, I might have written in unclear english, but i have a point and there is a flaw in the original text, I'm SURE what I have written can be improved. --Stefan ^talk 00:59, 28 July 2009 (UTC)

I'll start looking for sources for age as a risk factor. If we can find RS for all of the factors when applied to diving, then we can do away with the "altitude" qualifier - I would also be happy to see it go.

We are obliged to present multiple opinions if the sources don't all agree. You are quite right, though, WP:UNDUE says that we should not give undue weight to minority opinions, so the Leigh & Dunford study needs work to put it in context with the majority view.

Apologies, I read your edit summary differently from what you intended (I took the "also" to be part of the "alcohol not included aboive" point in your summary). You indeed have a point, but the text still isn't quite right. Let's see if we can find a better formulation. --RexxS (talk) 02:15, 28 July 2009 (UTC)

I agree, feel free to update, you are better than me at that! --Stefan ^talk 05:49, 28 July 2009 (UTC)

One more

Also this, in the Diagnosis section "In 1995, 95% of all cases reported to DAN had shown symptoms within 24 hours" and in the onset section "98% within 24 hours" in the table should be unified, both are right and referenced, but it would be better to have the same value for 24h in the article. I do not care which, only that we are consistant. --Stefan ^talk 14:10, 27 July 2009 (UTC)

It would indeed be better, but we can neither force DAN and TDI to agree on a figure, nor can we alter either source to make them fit for our convenience. The DAN source is a snapshot for the year 1995. The TDI summary has unknown provenance but may represent an earlier, later, or longer period. I'd be amazed if variations of percentages from 95% to 98% did not occur in different years. Don't let our enthusiasm for consistency overwhelm the need for accuracy in reporting what sources say. --RexxS (talk) 15:33, 27 July 2009 (UTC)

Obviously, but we can use only one source for both parts, but if you want to have two different statements in your enthusiasm for using RS then that is fine with me, good luck with GA or FA. --Stefan ^talk 01:08, 28 July 2009 (UTC)

I don't understand what you mean. Why can we only use one source for both parts? As for GA/FA, I'm pleased to say that Wikiproject Scuba now has its first FA (Oxygen toxicity) and that cited 125 sources! --RexxS (talk) 02:20, 28 July 2009 (UTC)

We do not need to get DAN to change or TDI to change, but we do not need to use both sources! I personally do not think that we should state 2 different facts, for the same thing in the same article. I think we should be consistent. My suggestion is to change the latter section to 98% of all cases had shown symptoms within 24 hours then the 2 sections will be saying the same (does not matter that both are probably wrong). But if you rather have both facts since both have good RS then nevermind, just my humble opinion.... I would guess that any GA/FA reviewer would find the same thing questionable and ask why, that is my point. --Stefan ^talk 05:47, 28 July 2009 (UTC)

last for now??

Suggested edit:

"Pre-breathing pure oxygen for 30 minutes before starting ascent to altitude reduces the risk of altitude DCS for short exposures (10 to 30 minutes only) to altitudes between 18,000 feet (5,500 m) and 43,000 feet (13,000 m). "

This again I'm sure is a direct quote from the source, but I will also reduce the risk of DCS if I pre-breath for 45 min, true? 15 min? and the whole 10 to 30 minutes and 18000 and 43000 feet is just like I would quote direct from a PADI table and state that DCS is reduced if I only stay for X minutes and Y depth, which we do not, we state that the longer we stay down and the faster we go up the more likley we are to get DCS. This is same case?? --Stefan ^talk 14:28, 27 July 2009 (UTC)

I hope we won't be stating that "DCS is reduced if I only stay for X minutes and Y depth" because it confuses the condition with its risk (and also because recreational tables, as opposed to military ones, are not risk-based). Anyway, I would support your proposed change, since the degree of quantitative detail is incongruous with the qualitative "reduces the risk of altitude DCS". The references that will support that will provide such detail. Go ahead! --RexxS (talk) 15:41, 27 July 2009 (UTC)